Summer zokor mounds as greenhouse gas hotspots compared to spring and autumn mounds on the Tibetan plateau

Abstract

Small subterranean mammals, such as plateau zokors, disturb grassland topsoil through mound creation, potentially elevating greenhouse gas emissions. While the ecological impacts of mounds have been studied in spring and autumn, little attention has been given to summer mound creation, a period of peak microbial activity and intensified plant–soil interactions. This knowledge gap limits the understanding of seasonal dynamics and mechanisms of greenhouse gas emissions in alpine ecosystems. In this study, the static chamber method was used to quantify net ecosystem exchange, ecosystem respiration, and CH₄ and N₂O fluxes from zokor mounds during spring, summer, and autumn, alongside measurements of soil, plant, and fauna communities. Results showed that summer mounds shifted the alpine meadow from a net CO₂ sink to a source, with CH₄ emissions (65.85 μg/m²/h), and N₂O emissions (52.81 μg/m²/h) all significantly higher than those from spring and autumn mounds. Net global warming potential increased on summer mounds, whereas spring and autumn mounds tended to reduce relative to intact pasture. The structural equation model indicated that zokor mounding reduced vegetation coverage and biomass, increasing net global warming potential and turning localized areas from greenhouse gas sinks to sources. To reliably evaluate the impacts of zokor mounds on greenhouse gases and their balances, it is crucial to consider the seasonal variation of mound creation. Additionally, reducing summer mound creation through appropriate grassland grazing management could help mitigate greenhouse gas emissions and lessen the ecological impact of zokor burrowing activity.